U.S. patent number 4,549,337 [Application Number 06/510,199] was granted by the patent office on 1985-10-29 for method of making a composite thread protector.
This patent grant is currently assigned to Alco Industries, Inc.. Invention is credited to William F. Matko, S. David Newell, James L. Onoratti, Lawrence H. Parrott.
United States Patent |
4,549,337 |
Newell , et al. |
October 29, 1985 |
Method of making a composite thread protector
Abstract
A composite dual wall cast urethane elastomer to metal thread
protector that will be practical under normal as well as frigid
temperature conditions of usage is formed by deep drawing a
seamless metal shell wall, using a threaded die to define a mold
cavity with the metal shell wall, forming and setting a synthetic
elastomeric shell wall within the mold cavity in an adhering
assembled relation with and along the metal shell wall with
threading that is complementary with threading of the die, removing
the assembly by unscrewing it with respect to the threaded die, and
subjecting the assembly to heat treatment to cure the elastomeric
shell wall and provide a composite protector having a cast urethane
elastomer wall in a secure adhering encapsulating relation on the
metal shell wall.
Inventors: |
Newell; S. David (DuBois,
PA), Matko; William F. (DuBois, PA), Onoratti; James
L. (Brockway, PA), Parrott; Lawrence H. (DuBois,
PA) |
Assignee: |
Alco Industries, Inc. (Valley
Forge, PA)
|
Family
ID: |
24029761 |
Appl.
No.: |
06/510,199 |
Filed: |
July 1, 1983 |
Current U.S.
Class: |
29/527.4;
138/96T; 264/268; 264/271.1; 264/552 |
Current CPC
Class: |
B29C
70/78 (20130101); F16L 57/005 (20130101); B29D
1/00 (20130101); B29C 43/00 (20130101); Y10T
29/49986 (20150115) |
Current International
Class: |
B29C
70/00 (20060101); B29C 70/78 (20060101); B29D
1/00 (20060101); B29C 43/00 (20060101); B22D
011/126 () |
Field of
Search: |
;29/527.4,527.2 ;138/96T
;264/266,552,268,269,271.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
8100822 |
|
Apr 1981 |
|
IB |
|
2093426A |
|
Sep 1982 |
|
GB |
|
Primary Examiner: Goldberg; Howard N.
Assistant Examiner: Rising; Vernon K.
Attorney, Agent or Firm: Parmelee, Miller, Welsh &
Kratz
Claims
We claim:
1. A method of making a composite elastomer to metal shell dual
wall thread protector for a threaded end of a pipe member that is
practical for use and reuse under elevated, normal and frigid
temperature conditions which comprises, deepdraw forming a metal
blank into an elongated cylindrical shell having a continuous
substantially closed end wall and an opposite substantially open
end wall, forming a casting assembly by placing the metal shell and
its closed end wall in a cooperating mold cavity defining relation
with respect to a hollow die having an opposed threaded side wall
therealong, introducing a normally thermoplastic synthetic
elastomer material in heat-liquidized form into and filling the
mold cavity along the threaded wall of the die, solidifying by
preliminarily heat-curing the elastomer material within the mold
cavity as an adherent wall casting along the metal shell wall and
forming a solidified elastomer to metal shell adherent dual wall
assembly therewithin, then removing the hollow die by unscrewing
the thus-formed elastomer to metal shell adherent dual wall
assembly with respect to the die, thereafter subjecting the
elastomer wall of the dual wall assembly to a final heat-curing
treatment, and effecting the heat-curing in such a manner as to
make the solidified elastomer wall fully thermosetting and to also
improve its resistance to chemicals such as encountered in the oil
fields.
2. A method as defined in claim 1 wherein, the elastomer material
is heated to its liquidized form before it is introduced into the
mold cavity, the elastomer material is solidified and preliminarily
hardened within the mold cavity by applying heat to the casting
assembly to form the adherent dual wall assembly with the metal
shell before the hollow die is removed and the final curing
treatment is thereafter effected by applying heat to the dual wall
assembly.
3. A method as defined in claim 2 wherein the preliminary
cure-hardening of the elastomer material within the mold cavity is
effected by applying heat thereto at a temperature of about
200.degree. F. for about fifteen minutes.
4. A method as defined in claim 3 wherein, after the hollow die has
been removed with respect to the dual wall assembly, the elastomer
wall casting of the dual wall assembly is subjected to a final
curing treatment at about 200.degree. F. for about sixteen
hours.
5. A method as defined in claim 2 wherein, before the elastomer
material is introduced into the mold cavity, an adhesive is applied
to a side of the metal shell that defines the cooperating mold
cavity with the hollow die, and the threaded wall of the die is
provided with a mold release material applied thereto.
6. A method as defined in claim 1 wherein, the metal shell is
deep-drawn to form a seamless metal cup, and a punch is applied to
the closed end wall of the cup to form tool receiving apertures
therein before the metal cup is placed within the hollow die.
7. A method as defined in claim 6 wherein the tool receiving
apertures are employed in aligning and retaining the metal blank in
a suitable mold cavity forming position within the hollow die.
8. A method as defined in claim 1 wherein, the mold cavity extends
longitudinally along the opposed threaded side wall of the die and
laterally inwardly with respect to the closed end wall of the metal
shell for a distance corresponding to a desired overlapping end
wall thickness of the dual wall assembly to thereby cast-form an
end flange of the elastomer material with respect to the closed end
wall of the metal shell.
9. A method as defined in claim 1 wherein, the hollow die is
positioned in an inwardly spaced relation with respect to an inner
side of the metal shell, and the threads are formed along an inner
side wall of the elastomer material of the dual wall assembly by
the die to provide a pin type of protector.
10. A method as defined in claim 1 wherein, the hollow die is
positioned in an outwardly spaced relation with respect to an outer
side of the metal shell, and the threads are formed along the outer
side of the elastomer material of the dual wall assembly by the die
to form a box type of protector.
Description
BACKGROUND OF THE INVENTION
This invention pertains to an improved protector for threaded pipe
members of a composite dual wall type. The improved protector is
suitable for preventing handling damage and corrosion and is also
suitable for use under sub zero and frigid temperature conditions,
such as encountered in the Arctic, and to a method of making
it.
An important phase of the invention deals with the making of a dual
wall composite thread protector in which a deep drawn metal shell
wall is encapsulated with an adherent threaded elastomeric wall for
mounting on an inside or outside threaded end of a pipe member.
DESCRIPTION OF THE PRIOR ART
It has been customary to employ a single wall metal collar type of
protector that is threaded on its outer or inner side for mounting
on an outside or inside threaded end of a pipe member. An improved
type of protector was developed by Henry Frishof which utilizes an
all metal construction which has inner and outer walls in a
spaced-apart relation, with one wall having threading for mounting
the unit on a pipe member. See U.S. Pat. No. 3,719,984. To give it
strength under low temperature utilizations, such as in the Arctic
or Anarctic, two metal shapes were deep drawn; the other one was
provided with threading and the two were then joined at their
forward nose ends by a continuous and smooth weld bead. This proved
to be a practical type of Arctic protector, particularly from the
standpoint that it is strong, has some flexibility, and enables the
use of pipe handling hooks, etc.
However, it has been determined that metal to metal threading
between a pipe member and its thread protector tends to promote
damage to the threads when the protector is damaged and, further,
permits corrosion to occur between the metal protector and the
threads of the pipe.
SUMMARY OF THE INVENTION
It has been an object of the present invention to provide an
improved type of thread protector that is suitable for use under
conditions of severe handling and corrosive, atmospheric and under
sub zero temperature conditions; that will be relatively
inexpensive to produce, and at the same time, will have an
acceptable period of life under conditions of use and reuse.
Another object has been to devise a basic thread protector
construction that is adaptable to both pin and box types of
utilizations wherein a protector is to be mounted on a threaded
male end or on an internally threaded female end of a pipe
member.
Another object of the invention has been to devise a type of thread
protector that facilitates mounting it on and thereafter removing
it from the threaded end of a pipe member.
A further object has been to provide a shock-resistant, composite,
dual wall protector having a backing metal shell wall and a fully
adhering threaded synthetic elastomeric wall that is of a shock
absorbent, somewhat flexible-elastic construction.
A still further object has been to better meet adverse factors
heretofore encountered in constructing and utilizing a so-called
Arctic type of thread protector, and to enable its relatively
inexpensive forming from a manufacturing standpoint.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a somewhat diagrammatic sectional view in elevation of
apparatus for preliminarily deep draw forming a metal cup or shell
wall from a flexible, disc-like metal blank;
FIG. 1A is a vertical sectional disclosing a second step in
producing a metal shell wall for either a pin or box type of
protector in accordance with the invention;
FIG. 1B is a sectional elevation illustrating the punch forming of
wrench holes in the base of the shell wall produced in accordance
with the step of FIG. 1A;
FIG. 1C is a vertical section illustrating the forming of an
inwardly curled rim or edge on the metal shell wall produced in
accordance with the step of FIG. 1B and which may be used in a
first independent step involved in producing a so-called box type
of thread protector;
FIG. 2 is a slightly enlarged diagrammatical section in elevation
illustrating the forming of an inner threaded elastomer wall part
in a die cavity defined by the metal shell wall of FIG. 1B and a
cooperating threaded, hollow die that defines a mold cavity
therewith; this operation deals with the forming of a composite
dual wall so-called pin type of protector in accordance with the
invention;
FIG. 2A is a view similar to FIG. 2, but discloses the forming of
an outer, threaded elastomer wall part within a mold cavity between
the metal shell wall of FIG. 1C and a cooperating, threaded hollow
die to produce a composite dual wall so-called box type of
protector in accordance with the invention;
FIG. 3 is a diagrammatic representation of a heat treatment oven in
which the assemblies of FIGS. 2 and 2A are to be introduced for
preliminarily solidifying, setting or hardening the elastomer wall
part in order to enable a screwingout removal of the threaded die
involved; this oven is also employed for imparting a final heat
treatment of the composite elastomer to metal dual wall assemblies
produced in accordance with the invention;
FIG. 4 is a sectional view in elevation illustrating the unscrewing
withdrawal of a dual wall protector assembly of a pin type with
respect to its forming die; and FIG. 4A is illustrative of the
unscrewing withdrawal of a dual wall protector assembly of a box
type from within and respect to its forming die;
FIG. 5 is indicative of typical impact testing to which specimens
of finished composite products produced in accordance with the
invention are subjected under normal temperatures and also under
cryogenic temperature conditions to impact loads of 400 pounds, as
applied axially, crosswise or angularly with respect thereto;
FIG. 6 is illustrative of the mounted relation of pin and box types
of protectors of the invention as applied to externally and
internally threaded ends of pipe members;
FIG. 7 is a greatly enlarged fragmental section illustrating a
structural phase of the invention from the standpoint of the
provision of lubrication cavities for a round or sharp V-EE type of
cooperative threading, as provided by an elastomer wall of a
protector with respect to the threaded end of a pipe member;
FIG. 8 is a view on the same scale as FIG. 7 also illustrating the
provision of lubricating cavities in which the threading is of a
so-called buttress or hydril type;
FIG. 9 is a horizontal fragmental section showing a thread
protector of the invention having an extending sealing collar and
lip and for sealing engagement with the smooth wall of a pipe
member; this construction is of a special type in which the
threaded elastomer wall part of the protector has a flexible,
extending, pipe-engaging, special sealing lip end portion;
FIG. 9A is a greatly enlarged view of a portion of the structure
shown in FIG. 9, particularly showing details of the construction
of the sealing lip;
And, FIG. 1O is an enlarged view similar to FIG. 9A illustrating an
under-projecting or under-fold type of sealing lip construction of
the elastomer wall.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1 of the drawings, a disc-like relatively thin
piece of metal 10, such as of steel, is preliminarily deep-drawn by
using a draw die 18, a blank holder 16, a draw punch 15 and ring 17
that is mounted on the face of the die 18. The resultant shell wall
of cup-like shape 11, shown in dotted lines in FIG. 1 and in full
lines in FIG. 1A, is then deep-drawn to form a further elongated
shell wall or cup 12, having two diameters, assuming that the pipe
member to which it is to be applied, has two threaded diameters
(see FIG. 6). The cup 12 formed by a draw punch 19 and draw die 20
is then placed in a punch assembly of FIG. 1B that employs a punch
21, a die 23, and a holding and shape retaining die 22. The punch
21 is then introduced into the open end of the cup shape 12 and its
aperture forming tips 21a are advanced through its closed end to
form a pair of so-called tool or wrench-receiving, spaced-apart
apertures or slots 12a therein. The shell wall or cup 12 thus
formed may be used to alternately form a composite pin or box type
of thread protector. If a box type of protector is to be provided
with a curled lip or open edge, it may be formed in accordance with
FIG. 1C by the use of a base support 25a and a deep-drawing die 25
as employed with a draw punch 24.
FIGS. 2 and 4 show steps involved in providing a so-called pin type
of composite thread protector, while FIGS. 2A and 4A are
illustrative of the forming of a so-called box type. Referring to
FIG. 2, a support stand 28 is shown which carries a pair of pilot
pins that are adapted to align with the apertures 12a in the base
of the metal shell 12 for the purpose of maintaining the parts in
an aligned relation with respect to the support member 28. A hollow
metal mold or casting 26 is shown centrally mounted within and in
an opposed, inwardly spaced-apart, die cavity forming relation with
respect to the deep-drawn metal shell wall 12. A suitable synthetic
elastomer, such as polyurethane in liquidized form is then poured
into the mold cavity and the cavity closed by a lid 29 which fits
on an upper end of the mold wall 26. The lid 29 may be temporarily
secured in a closing-off relation with respect to the mold 26 by
bolt or threaded screw means 29a.
The full assembly is then introduced into a curing oven 35 for a
short period sufficient to cure-harden the elastomer to form an
encapsulating wall 14 in an adhering relation about the inside of
the metal shell wall 14. Thence, the unit of FIG. 2 is removed from
the oven 35 and the dual plastic to metal wall assembly 12, 14 is
then removed from the mold by relatively unscrewing them with
respect to each other as shown in FIG. 4. Thereafter, the composite
dual wall protector assembly 12, 14 is given a long term heat
treatment in the oven 35, being introduced through its door 36, to
make the elastomer wall 14 fully thermosetting and finalizing its
treatment to such an extent that it will have desired
characteristics and will constitute a shock-absorbent, and
elastic-flexible integral part of the metal shell 14.
FIG. 2A and 4A show further procedure for making a so-called box
type of composite dual wall protector, using the shell wall 13. A
hollow metal casting 30 has a bottom plate 31 removably secured
thereto, as by bolts or threaded screws 31a. The metal shell wall
13 is positioned within the mold casting 30 in an inwardly
spaced-apart mold cavity defining relation, and synthetic elastomer
material in liquid form is then poured into the mold 30 through a
side orifice 30a to fill it, as shown in FIG. 2A. The bottom plate
31 of the mold casting has a supplemental piece 31b projecting
upwardly therefrom to limit the filling up of the elastomer within
the cavity so as to provide an open end portion in the elastomer
layer 33, see particularly FIG. 4A. Aligning or pilot pins 32 are
carried by the piece 31b and are adapted to align and fit within
the apertures 13a in the metal shell 13 to align the shell 13 with
respect to the casting 30 prior to the pouring operation.
Similar to the treatment effected as to the resin layer of the
embodiment of FIG. 2, the assembly of FIG. 2A is introduced through
door 36 into the curing oven or furnace 35 and retained therein for
a short period to solidify and cure-harden the elastomer wall 33,
after which the assembly is removed from the oven. The dual wall
assembly 13, 33 is then removed from the casting mold 30 by
unscrewing them with respect to each other as shown in FIG. 4A. The
dual wall assembly 13, 33 is then introduced into the oven 35 and
given a long term curing treatment to provide the elastomer layer
33 with its requisite properties.
In FIG. 6, the left hand portion of a pipe member B having a two
tier threading is shown provided with a composite thread protector
A of a pin type of the invention in a fully mounted position
thereon. This mounting is effected by inserting a tool or wrench
having projecting pins into the apertures 12a of the metal shell
wall 12. The right hand portion of FIG. 6 shows a pipe member D
having female or internal threading of a two tier type with a
composite thread protector C of a box type of the invention in a
mounted position therein. The mounting and dismounting of the unit
C is also effected by a wrench or tool having projecting pins that
extend into the apertures 13a that were previously formed in the
metal shell wall 13 of the unit.
Basis of the Invention
The present structure has been developed to meet the need for an
improved thread protector that will withstand either high or
frigid-cryogenic temperatures and, at the same time, will have a
long period of life from the standpoint of its use and reuse, and
further that will give a maximum amount of protection to the
threaded ends of a pipe member during storage, and movement from
place to place prior to the employment of the member in building a
pipe line. We decided the best approach was to provide a composite
type of wall structure in the protector, as based on the use of an
elastomer-to-metal wall in a secure abutting relation with respect
to each other, and employing the elastomer wall or layer as the
threaded part of the structure. By so doing, it has been determined
that difficulties heretofore encountered in the use of a
metal-to-metal relation in effecting a screwing on and off of a
thread protector employing cooperating steel or metal-to-metal
threading can be eliminated, and a less expensive and a better and
more protective type of construction could be attained by the use
of such a composite design in which the threading is provided by an
elastomer wall thereof.
Having arrived at the above analysis, a second factor involved in
attaining a solution to the problem rested on how an elastomer
to-metal type of construction could be effected economically and,
at the same time, would meet criteria of a substantially seamless,
one-piece construction having the ability to stand up under impact
and temperature conditions such as encountered. Having determined
that a seamless type of metal shell was important, we developed a
procedure in which it is first formed by deep-drawing operations
and is then employed as one wall of a die cavity in forming an
adhering synthetic elastomer wall therewith. The elastomer wall is
formed between the metal shell wall and an opposite threaded wall
portion of a die casting part, with the elastomer being threaded
and formed in such a manner that it provides an abutting,
encapsulating, somewhat flexible, shock absorbing wall about the
metal shell wall that can be easily removed from the threaded
casting part by a simple unscrewing operation.
Another factor in solving the problem involved the determination of
a synthetic elastomer that would have characteristics of toughness,
hardness, mar resistance, flexibility and resistance to chemical
action, aging and adaptability to absorb shock and, at the same
time, could be easily cast into a somewhat complex threaded shape.
It also must be thermosetting as formed on the metal shell wall. In
this connection, we determined that polyurethane complied with the
above requirements, but is normally thermoplastic. We, however,
developed a heat treatment procedure which renders it fully
thermosetting and improves its resistance to chemicals, aromatics
and other products, such as encountered in the oil fields; it also
has good resistance to weathering, etc. and can be adhesively
secured to the metal shell wall.
Although the process of the invention has been particularly
illustrated from the standpoint of a stepped type of threading, it
should be recognized that it can be made for any proprietary type
of threading in accordance with the invention disclosed.
As to specifics, a polyurethane resin in granular form as sold by
Mobay Chemical as its E520, and as used with an extender hardening
agent, such as butane diol may constitute the resin material in
liquid form that is poured into the mold. The resin material may be
liquified by heating it in a heated pressure vessel and dispensing
it through a heated metallic hose into the applicable mold cavity.
A suitable adhesive, such as Phixon No. 405, sold by Whittaker
Corporation, Dayton Coatings and Chemical Division of W.
Alexandria, Ohio 45381 has been found to be satisfactory for
application to the side of the metal shell wall that is to be
adhered to the resin wall. It is also advantageous to use a
suitable protective coating of talc or the like as applied to the
opposed surface of the die casting part or element that is used.
This enables a free and easy unscrewing removal of the composite
protector unit with respect to the threaded casting. However, any
suitable so-called mold release material may be used. We have found
that approximately fifteen minutes preheating treatment at about
200.degree. F. in the oven 35 is sufficient to solidify and adhere
the synthetic resin to the metal shell wall 12 or 13, preliminary
to the steps of FIGS. 4 and 4A. Thereafter, however, it is
important to place the composite dual wall protector in the oven 35
once again and to hold it therein for a final curing-conditioning
treatment at about 200.degree. F. for about sixteen hours.
The possibility of using another type of resin, such as expanded
polystyrene has been considered. However, polyurethane, as used in
accordance with the disclosed curing process has been found to be
superior in every respect as suitably heat-treated to meet the
criteria involved. This has been proven by so-called cyrogenic
testing of a completed protector which involves the application of
a 400 lb. weight dropped from a height of about four feet on a
protector unit endwise and also crosswise. Finally, a so-called
point contact type of application has been applied by placing a
two-inch diameter steel bar across its end and then dropping a
weight of about 400 lbs. from a height of about four feet. Also,
testing has been conducted applying and dropping a weight of 250
lbs. from a height of about two feet in such a manner as to direct
the force against an edge of the resin wall at an angle about over
15.degree.. This provides a stripping test. The above testing has
also been effected at about -50.degree. F. to fully prove the
efficacy of the composite construction and of the procedure
involved in fabricating it.
FIG. 6 of the drawing illustrates an important feature of the
invention, both from the standpoint of a pin type, as well as a box
type of thread protector. As to the pin type A, it will be noted
that the elastomer-threaded layer or inner wall when mounted on the
pipe member B has elastic sealing portions at its opposite ends to
thus prevent dirt, moisture, etc. from entering the cooperating
threaded area. As shown, the elastomer wall 14 has a transversely
inwardly extending elastic or flexible sealing rim 14a at its back
end that is adapted to abut the butt end of the pipe member B, and
has a forwardly extending smooth elastic sealing lip portion 14a at
its other end that is adapted to closely abut in tight frictional
sealing engagement with the smooth cylindrical wall portion of the
pipe member B, beyond the cooperating threading. In a similar
manner, the box protector C has a threaded elastomer layer or outer
wall 33 that, at its forward end, has a transversely outwardly
projecting elastic sealing lip or rim 33a which is adapted to
tightly abut the forward butt end of the pipe member B. It also has
a shouldered, transversely inwardly projecting or turned elastic
rim or flange portion 33b which is adapted to tightly flexibly abut
the unthreaded smooth wall portion of the pipe member D beyond the
threading thereof.
The above constructions have been found to be highly important in
the art and, along with the flexible construction of the threaded
wall of the thread protector of the invention, assures an easy "on"
and "off" mounting of the protector on the associated pipe member.
They avoid difficulties which arise from the standpoint of the
introduction of dirt and other contaminants between the threads
when the pipe is being handled or stored with thread protectors
mounted on its ends.
FIGS. 7 and 8 illustrate a further feature that may be incorporated
in the construction of the invention, namely, the provision of
so-called lubricating cavities between at least one wall of the
threading of the pipe member D and an opposed wall of the threading
of the thread protector E or E'. In these two figures, a and a'
represent threaded wall portions of the elastomer wall E or E'
which are formed in the casting procedure to provide clearance
areas, spaces or cavity portions with respect to corresponding
threaded portions of the pipe member D. On the other hand, b and b'
represent areas of the threading which are the load bearing areas
and serve to secure the protector in a sealing-off position on the
pipe member. In this construction, it is important to provide at
least one riser portion b or b' along the cooperating threading
with a close abutting engagement. The provision of cavity areas
such as a and a' further facilitates easy mounting and dismounting
of the thread protector and provides areas in which a thread joint
compound of lubricating material may be used.
In FIGS. 9, 9A and 10, we have illustrated a modified form of
construction which has what may be termed a longtitudinal lip end
engagement of the elastomeric wall with a pipe member B, as
provided by an endwise, backwardly projecting, neck, collar or
sleeve portion d that has a sealing lip end e or f. As shown, the
sealing lip e is held in tight engagement with the pipe member B
along its smooth wall portion and beyond the mounting of thread
protector F by the extending wall or collar portion d that is
resilient. In FIGS. 9 and 9A, engaging sealing lip e is of rounded
semi-circular shape, while in the embodiment of FIG. 10, the lip f
constitutes an underturned end portion that provides somewhat of a
feather edge type of engagement with the smooth wall of the pipe
member B.
* * * * *